A Tuning Guide for Noobs / Tuning HOWTO
Disclaimer: Tuning is where my knowledge of things starts to get thin. My goal for this thread is to provide links to information I found useful and then try to give a different slant on the fundamentals in an effort to make understanding the tuning process easier for noobs. Please be sure you understand this stuff well before you try tuning on your own. Take responsibility for your own actions!
Tuning Links on PGMFI
It goes without saying that you should read the entire Wiki many times until you understand everything. I've also included some links here that proved very helpful for me. Keep in mind that even the data here should not be trusted 100%. Question everything until you understand! There were a couple of points here and there that I don't agree with - but I could be wrong, too.
The Ickyhonda Tuning Guide.
Blundar's tuning Theory.
Jeff Evnas Tuning.
ECT correction tables explained by blundar.
Tuning advice from bigwig for a B16 motor, good advice on timing in last post. Bad links to pics of fuel and timing tables.
Car tuned on Mustang Dyno by blundar - some tuning explanation included.
Spark plug reading HOWTO.
D16Z6 timing.
General tuning procedure explained.
Author of Progress of a Simple Minded Noob asks about timing.
Open vs. closed loop question. Setting Open/Closed loop switch-over in Crome.
Fighting detonation. Winter vs. summer tune idea.
Extra Features plugin - stickied in Crome forum.
Tuning HOWTO, short explanation on RPM and load control.
Street Tuning tips, plug reading links. More Simple Minded Noob stuff.
Datalogging HOWTO.
Some good tuning theory. - A lot of bashing! If you can make it through the banter you will find a couple of gems of knowledge. Theory on fooling the ECU into using other AFRs in closed loop operation using a programmable LC1 output. Klatinn gives some good input to end any disputes.
Using Autotune - mostly success stories, some theory about crossing lines in maps, etc. Need quick laptop.
Knock logger not worth much. A little on detonation and a plug reading link. Deluded gives some data about plug selection.
General guidelines, some info on EGT and timing, wbo2 and fuel tuning.
DIY Det can HOWTO.
Books on Tuning
I have read these books and recommend them. The second book has a short section on tuning procedure and is the only book I've found that addresses it at all. There are probably more good books to reference. Please PM links if you have some.
Maximum Boost: Designing, Testing, and Installing Turbocharger Systems
How to Tune and Modify Engine Management Systems
Introduction to Internal Combustion Engines
Classes on EFI
The only class I'm aware of is held in locations around the country. Just log on to their site and pick a time and a place. I haven't been to the class, but think it might be fun to take one day. Do a search to see what others think of it. You'll find both good and bad feedback on the class.
EFI101 - EFI University
Engine Basics from 10,000 Feet
Engines are complicated machines that convert chemical energy into mechanical energy. There are many factors that determine how a combustion engine will behave at any given point in time. Things like amount of fuel in the combustion chamber, amount of oxygen in the combustion chamber, the temperature of the air, the timing of the spark, the load on the engine, and the humidity are only a start to a long list of items that determine how a motor functions. Tuning an ECU is the art of controlling certain parameters to make the engine perform in a desired manner.
We can only control a relatively small number of parameters to the engine from the ECU. The main things we can control are the amount of fuel that enters the combustion chamber, and when spark is applied to that charge. The ECU's purpose is to manipulate these parameters in relation to many other environmental factors to yield the best result. The best result is defined as maximum power, best fuel economy, lowest emissions, safest operation, or any combination thereof.
Since the ECU must manipulate fuel and spark delivery in relation to other environmental factors, it must measure those other factors. Parameters that the ECU must measure are the amount of air flowing into the engine (via MAF or MAP), IAT (Intake Air Temperature), ECT (Engine Coolant Temperature), TPS (Throttle Position Sensor), Engine Speed (RPM - tach), Engine Position (via Crank position sensor or distributor signal), and engine load (MAP), to name a few. The ECU may also check the status of other items such as oil pressure and/or knock sensor to make sure nothing dangerous can happen to the motor, but these don't need to be considered during the tuning process.
The main things that tuners manipulate to change the way their motor behaves are fuel and timing. The ECU must be instructed how these two things should be controlled for many different combinations of the parameters listed above. The manner in which the ECU is given this instruction varies by motor and ECU type.
This thread focuses on the Speed Density paradigm, since that's what most, if not all, OBD1 Honda engines use. Speed Density systems manipulate fuel and spark based on two main parameters: MAP sensor output and RPM.
The ECU uses tables for fuel and spark which are indexed by MAP and RPM sensor readings. Tables are a very simple way for computers to determine how they should behave for any combination of input parameters. In a Honda Speed Density system, at any given time the ECU finds the row associated with the current RPM and the column associated with the current MAP reading, takes the data at the intersecting point, and uses that to deliver the right amount of fuel or timing. The ECU does this in rapid succession, over and over again, to make the engine run.
Of course, other parameters play a factor in how much fuel or timing must be delivered to the engine, but these factors are less significant and usually result in a simple mathematical manipulation of the value obtained from the table lookup.
Engine Basics - Summary
What does all this mean? In a nutshell, tuning is the art of controlling the many different parameters that affect engine functionality, making changes to fuel and timing tables, and ensuring that the desired results are achieved by taking measurements that paint a picture of how the motor is performing. It's making changes to the instructions given to the ECU so that the motor will perform best.
Remember your science experiments in school or College? Remember the Scientific Method? All that stuff is very useful for tuners. The better you are at controlling parameters that affect your engine and manipulating them one by one in a safe manner, the more you will understand its operation and be able to affect it the way you want. For tuners, that means making sure the AFR (Air Fuel Ratio) and timing are set safely and the motor makes lots of usable power.
Fuel and Timing Basics
A motor wants to run at stoich most of the time. In very basic and somewhat loose terms, the stoich fuel mixture is one that burns most completely in the combustion chamber and will yield highest efficiency. The value of stoich varies depending upon fuel type. For the purposes of this post, we'll use 14.7:1, which means 14.7 parts of air to 1 part fuel for pump gasoline. Motors like to run a little richer than stoich when they are required to work harder.
Spark must be delivered to the combustion chamber at just the right time if the fuel and air in the chamber are to burn in a manner that will make the engine turn safely. If the spark is too early or too late, the motor will generate less torque (twisting force) and/or be damaged, depending upon how premature or late the spark is. In general, as the engine turns faster spark should be delivered sooner.
Spark timing is always measured relative to a certain rotational position of the motor. We call this position TDC (top dead center), which is when the piston in the number one cylinder is in its highest position. Since we want to ignite the air/fuel mixture at approximately TDC, we need to create a spark in the combustion chamber before the piston gets there - it takes time for the air and fuel to ignite and start expanding. The faster the motor is turning, the earlier the spark will have to be initiated if the intake charge is to properly ignite at the correct motor position. Changes in timing can make big changes in how much power the motor makes. Improperly setting the timing can destroy a motor, too.
The relationship between engine RPM and spark advance is explained by the formula 'd = v * t', where 'd' is the distance before top dead center, 'v' is the speed of the motor (RPM), and 't' is the time it takes for the air/fuel to ignite. Let's assume for now that 't', or the time it takes for the air/fuel to ignite, is constant. We see that as the RPM (v) increases 'd', which is the amount of spark advance that is required, will increase in proportion. Think about it for a moment - remember those physics classes?
BTW - 't' isn't really constant because the air/fuel mixture takes different amounts of time to ignite depending upon other factors such as charge density and temperature, but those are less significant details you can learn about as you get more advanced.
What Do Tuners Do?
In summary, as a tuner your goal is to set the fuel and timing maps so your engine runs right. There are other parameters you may have to change too, like ECT and IAT compensation, idle speed, red line RPM, etc. These items will differ depending upon the motor, ECU, and vehicle you are tuning. You'll have to read, study and experiment to get them right.
Tools of the Trade
How do you know when you are changing things the right way? You must rely on sensors to give you feedback into how the motor is behaving. The main sensors you will use as a tuner are a wbo2 (Wide Band O2) sensor, possibly and EGT (Exhaust Gas Temperature) sensor and a det can, which can be your ear in some cases. You need to ensure that the AFR (Air Fuel Ratio) measured by your wbo2 is correct (quite often stoich, but not always), your EGT isn't too high, and that the engine isn't detonating. Of course the generation of peak torque is always a good thing, too. This can be measured by accelerometers (like a GTech), a butt dyno, a timing device, or preferably a real dyno.
Refer back to earlier posts from this thread for a shopping list of things you might purchase to start tuning. A wbo2 is essential for tuning - trying to tune without one is asking for big trouble. $200 for an LC1 is a small investment to make when you consider the alternative.
The more data you can get while tuning, the better picture you'll have about what's going on inside your motor. Getting datalogging working on your ECU will give lots of data that can help you figure out what your motor needs in any given situation. Datalogging will enable you to record all your sensors in relation to each other so you can study how they work and interact with each other even after your motor has stopped running. It is an invaluable tool and will teach you a lot about how motors work.
In addition to the ECU sensors, I log readings for fuel pressure, AFR via an LC1 wbo2, and EGT. Although I don't have a det can, I would like to have one. There's a link to build one above. Be creative and have fun while you learn!
More Tuning HOWTO to Come
I'll try to give some tips and a use scenario tuning with Crome shortly. I have been tuning my car using Crome - it seems to be running great now. I still have more tweaking to do, but am very happy with the progress I have made. I am making more HP using Crome than I was using an FMU. Best of all I am prepared to start safely adding more boost to build more power, which couldn't be done with my previous configuration. Stay tuned...
